The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 02, 2001
Filed:
Jan. 13, 1999
George Ploussios, Andover, MA (US);
Other;
Abstract
A collinear electronically tunable helical antenna system includes at least one helical antenna coil; a center conductive tube disposed axially through the open center space of the coil, which may contain bias and control lines and feed lines. The antenna coil is short circuited to the center tube near the base of the coil, forming a tunable choke. Sections of the coil are shorted to electrically shorten the coil, thereby tuning the antenna and choke. Each antenna coil is powered via feed lines that emanate from the antenna base and which run through the conductive tube from below the antenna base. Sections of coil may be shorted by a pair of oppositely poled diodes forming a PIN diode switch connected across a section of antenna coil. A bias voltage that controls the switch is supplied to the switch, via bias lines which run within the antenna coil and exit the antenna coil at a point symmetrical between each pair of oppositely poled diodes. The bias voltage is adjusted to permit the PIN diode switch to provide a short circuit across the selected section of coil thus changing the operating frequency of the antenna and choke. No rf current is directly induced in the conductive tube beyond the choke (and open end) of the antenna coil. Additional independently controlled antennas and other devices may therefore be mounted, without mutual interference, along the conductive tube.